2-178671134-T-G

Variant names:

• chr2-178671134-T-G
• rs189966800
• NM_001267550.2:c.35264A>C

Variant summary

Our verdict is Benign. Variant got -9 ACMG points: 0P and 9B. BP4_Strong BP6 BS1

The NM_001267550.2(TTN):​c.35264A>C​(p.Lys11755Thr) variant causes a missense change. The variant allele was found at a frequency of 0.000342 in 1,604,464 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.0018 (1 hom., cov: 32)
  • Exomes 𝑓: 0.00019 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3 B:15
• Conservation: PhyloP100: 3.64

Genes affected

TTN (HGNC:12403): (titin) This gene encodes a large abundant protein of striated muscle. The product of this gene is divided into two regions, a N-terminal I-band and a C-terminal A-band. The I-band, which is the elastic part of the molecule, contains two regions of tandem immunoglobulin domains on either side of a PEVK region that is rich in proline, glutamate, valine and lysine. The A-band, which is thought to act as a protein-ruler, contains a mixture of immunoglobulin and fibronectin repeats, and possesses kinase activity. An N-terminal Z-disc region and a C-terminal M-line region bind to the Z-line and M-line of the sarcomere, respectively, so that a single titin molecule spans half the length of a sarcomere. Titin also contains binding sites for muscle associated proteins so it serves as an adhesion template for the assembly of contractile machinery in muscle cells. It has also been identified as a structural protein for chromosomes. Alternative splicing of this gene results in multiple transcript variants. Considerable variability exists in the I-band, the M-line and the Z-disc regions of titin. Variability in the I-band region contributes to the differences in elasticity of different titin isoforms and, therefore, to the differences in elasticity of different muscle types. Mutations in this gene are associated with familial hypertrophic cardiomyopathy 9, and autoantibodies to titin are produced in patients with the autoimmune disease scleroderma. [provided by RefSeq, Feb 2012]

TTN-AS1 (HGNC:44124): (TTN antisense RNA 1) This gene encodes a non-coding RNA transcribed from the opposite strand to the titin gene. [provided by RefSeq, Aug 2016]

LOC124906100 (HGNC:):

ACMG classification

Verdict is Benign. Variant got -9 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.006884694).
• BP6: Variant 2-178671134-T-G is Benign according to our data. Variant chr2-178671134-T-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 46914.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=5, Benign=8, Uncertain_significance=3}. Variant chr2-178671134-T-G is described in Lovd as [Likely_benign].
• BS1: Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.00183 (278/151954) while in subpopulation AFR AF= 0.00628 (261/41536). AF 95% confidence interval is 0.00566. There are 1 homozygotes in gnomad4. There are 120 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.35264A>C	p.Lys11755Thr	missense_variant	Exon 156 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.35264A>C	p.Lys11755Thr	missense_variant	Exon 156 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes AF: 0.00183 AC: 278 AN: 151836 Hom.: 1 Cov.: 32

Gnomad AFR AF: 0.00630

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000724

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000295

Gnomad OTH AF: 0.00191

GnomAD3 exomes AF: 0.000437 AC: 104 AN: 238212 Hom.: 0 AF XY: 0.000347 AC XY: 45 AN XY: 129674

Gnomad AFR exome AF: 0.00623

Gnomad AMR exome AF: 0.000347

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.0000469

Gnomad NFE exome AF: 0.00000914

Gnomad OTH exome AF: 0.000178

GnomAD4 exome AF: 0.000186 AC: 270 AN: 1452510 Hom.: 0 Cov.: 30 AF XY: 0.000154 AC XY: 111 AN XY: 722444

Gnomad4 AFR exome AF: 0.00682

Gnomad4 AMR exome AF: 0.000394

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000119

Gnomad4 FIN exome AF: 0.0000188

Gnomad4 NFE exome AF: 0.00000361

Gnomad4 OTH exome AF: 0.000384

GnomAD4 genome AF: 0.00183 AC: 278 AN: 151954 Hom.: 1 Cov.: 32 AF XY: 0.00162 AC XY: 120 AN XY: 74278

Gnomad4 AFR AF: 0.00628

Gnomad4 AMR AF: 0.000723

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000295

Gnomad4 OTH AF: 0.00189

Alfa AF: 0.000330 Hom.: 1

Bravo AF: 0.00233

ESP6500AA AF: 0.00501 AC: 18

ESP6500EA AF: 0.000123 AC: 1

ExAC AF: 0.000613 AC: 74

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:3 Benign:15

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not specified Benign:6

Jul 19, 2021

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: TTN c.31361A>C (p.Lys10454Thr) results in a non-conservative amino acid change located in the I-band region of the encoded protein sequence. Three of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 0.00044 in 238212 control chromosomes, predominantly at a frequency of 0.0062 within the African or African-American subpopulation in the gnomAD database. The observed variant frequency within African or African-American control individuals in the gnomAD database is approximately 16-fold of the estimated maximal expected allele frequency for a pathogenic variant in TTN causing Dilated Cardiomyopathy phenotype (0.00039), strongly suggesting that the variant is a benign polymorphism found primarily in populations of African or African-American origin. To our knowledge, no occurrence of c.31361A>C in individuals affected with Dilated Cardiomyopathy and no experimental evidence demonstrating its impact on protein function have been reported. Six ClinVar submitters (evaluation after 2014) cite the variant as benign/likely benign and one ClinVar submitter (evaluation after 2014) cites it as uncertain significance. Based on the evidence outlined above, the variant was classified as benign. -

Nov 12, 2019

Athena Diagnostics

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jun 24, 2013

Biesecker Lab/Clinical Genomics Section, National Institutes of Health

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: research

- -

Dec 16, 2014

Eurofins Ntd Llc (ga)

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Nov 13, 2017

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

p.Lys10454Thr in exon 151 of TTN: This variant is not expected to have clinical significance because it has been identified in 0.6% (142/22990) of African chrom osomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute. org; dbSNP rs189966800). BA1 -

-

Clinical Genetics, Academic Medical Center

Significance: Benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

not provided Benign:3

Mar 28, 2023

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

-

Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center

Significance: Likely benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Dec 03, 2020

GeneDx

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is associated with the following publications: (PMID: 23861362) -

Autosomal recessive limb-girdle muscular dystrophy type 2J Uncertain:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Dilated cardiomyopathy 1G Uncertain:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Early-onset myopathy with fatal cardiomyopathy Uncertain:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Benign:1

Jan 29, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Cardiomyopathy Benign:1

Sep 08, 2016

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Tibial muscular dystrophy Benign:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. -

Myopathy, myofibrillar, 9, with early respiratory failure Benign:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. -

Primary dilated cardiomyopathy Benign:1

-

Genetics and Genomics Program, Sidra Medicine

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: research

- -

Cardiovascular phenotype Benign:1

Nov 08, 2013

Ambry Genetics

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This alteration is classified as likely benign based on a combination of the following: population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.58
BayesDel_addAF	Benign	-0.30	T
BayesDel_noAF	Benign	-0.20
CADD	Benign	21
DANN	Uncertain	1.0
Eigen	Benign	0.099
Eigen_PC	Uncertain	0.23
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Benign	0.44	T;T;.;T
M_CAP	Uncertain	0.11	D
MetaRNN	Benign	0.0069	T;T;T;T
MetaSVM	Benign	-0.78	T
PrimateAI	Uncertain	0.58	T
PROVEAN	Uncertain	-3.0	D;.;.;.
REVEL	Benign	0.27
Sift	Pathogenic	0.0	D;.;.;.
Polyphen		0.74	.;.;P;P
Vest4		0.36
MVP		0.45
MPC		0.16
ClinPred		0.13	T
GERP RS		4.8

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs189966800; hg19: chr2-179535861;